where \(R_{\rm P(AP)}=1/G_{\rm P(AP)}\)  is the resistance for the P
(AP) case. The conductance can be calculated by using the nonequilibrium
Green's function method [1]} as
\(G=\frac{e^2}{h}\int _{-\infty }^{+\infty }dE{\cal T}(E) \left(-\frac{\partial }{\partial E}f(E-E_{\rm F})\right),\) 
